#include <iostream>

using namespace std;

class Solution
{
public:
    int fib(int n)
    {
        if (n == 0)
            return 0;
        int v1 = 0;
        int v2 = 1;
        for (int i = 0; i < n - 1; i++)
        {
            int v = v1 + v2;
            v1 = v2;
            v2 = v;
        }
        return v2;
    }
};
int main()
{
    cout << "Code509" << endl;
    Solution s;
    return 0;
}